The present invention relates to a self-test circuit. More particularly, but not exclusively, the present invention relates to a self-test circuit for monitoring the output of a plurality of components, such as relay driver outputs using a single input to a monitoring device.
Self-testing is generally viewed as being advantageous, particularly noninvasive self-tests. Self-test circuits allow a device to be tested without requiring specialized testing devices. A self-test circuit allows a device to be tested either during manufacturing, during servicing, or both during manufacturing and servicing. Self-testing also typically allows tests to be performed quickly and inexpensively which are particularly important in the manufacturing context. For example, a single self-test may replace testing a circuit at numerous test points, thereby reducing the time and cost of testing.
Nevertheless, there are problems with implementing self-test circuits. These problems generally relate to the increased complexity and cost of circuits that incorporate self-testing functionality. For example, adding self-testing to a device may require adding a separate microcontroller for the limited purpose of self-testing. This addition adds significant cost to the device. Existing microcontrollers in an apparatus may not be useable for self-testing because there are insufficient available inputs for the microcontroller. In such an instance, one alternative may be to use a different microcontroller with expanded input capabilities, but doing so would also likely increase the cost and complexity of the device. Therefore, there are problems with incorporating self-test circuits into electronically controlled devices.
Thus, it is a primary object, feature or advantage of the present invention to improve upon the state of the art.
It is a further object, feature or advantage of the present invention to provide a self-test circuit suitable for use in various devices, including household appliances.
Another object, feature or advantage of the present invention is to provide a self-test circuit that minimizes additional cost and complexity.
Yet another object, feature or advantage of the present invention is to provide a self-test circuit that requires only a single input to a microcontroller to test multiple components such as relay drivers.
A still further object, feature, or advantage of the present invention is to provide a self-test circuit that is noninvasive.
One or more of these and/or other objects, features, or advantages of the present invention will become apparent from the specification and claims that follow.